1 // SPDX-License-Identifier: GPL-2.0-only
3 * Based on arch/arm/mm/mmap.c
5 * Copyright (C) 2012 ARM Ltd.
9 #include <linux/memblock.h>
11 #include <linux/types.h>
13 #include <asm/cpufeature.h>
17 * You really shouldn't be using read() or write() on /dev/mem. This might go
20 int valid_phys_addr_range(phys_addr_t addr, size_t size)
23 * Check whether addr is covered by a memory region without the
24 * MEMBLOCK_NOMAP attribute, and whether that region covers the
25 * entire range. In theory, this could lead to false negatives
26 * if the range is covered by distinct but adjacent memory regions
27 * that only differ in other attributes. However, few of such
28 * attributes have been defined, and it is debatable whether it
29 * follows that /dev/mem read() calls should be able traverse
32 return memblock_is_region_memory(addr, size) &&
33 memblock_is_map_memory(addr);
37 * Do not allow /dev/mem mappings beyond the supported physical range.
39 int valid_mmap_phys_addr_range(unsigned long pfn, size_t size)
41 return !(((pfn << PAGE_SHIFT) + size) & ~PHYS_MASK);
44 static int __init adjust_protection_map(void)
47 * With Enhanced PAN we can honour the execute-only permissions as
48 * there is no PAN override with such mappings.
50 if (cpus_have_const_cap(ARM64_HAS_EPAN)) {
51 protection_map[VM_EXEC] = PAGE_EXECONLY;
52 protection_map[VM_EXEC | VM_SHARED] = PAGE_EXECONLY;
57 arch_initcall(adjust_protection_map);